Tappet.



G. R. RICH.

TAPPET. APPLICATION FILED SEPT- 18. I916- Pateniefi Feb. 6,1917.

UNTTED TAS PATENT @FFTQE GEORGE BsRICH, 01? OAK PARK, ILLINOIS.

TAPPET.

Application filed September 18, 1916.

To all who-m it may concern:

Be it known that I, GEORGE R. RICH, a citizen of the United States, anda resident of Oak Park, county of Cook, and State of Illinois, haveinvented cert-ainnew and useful Improvements in Tappets, of which thefollowing is declared to be a full, clear, and exact description.

This invention'relates to tappets of that kind adapted for use inconnection with puppet valves of internal combustion engines.

lit is well known to those skilled in the art to which this inventionpertains that case-hardened valve tappets used in high speed motors areacted upon by the cams at extremely frequent intervals while the motoris running; moreover, that a strong, tough body is required and that thehead portion or flange, which-rides upon the cam, must be hard. In highspeed motors the speed is so great that quite frequently the valvetappets are unable to follow the cams, because for one reason, thesprings, which seat the valves and depress the tappets, do not actquickly enough to maintain continuous contact between the heads of thetappets and cams. the friction between the tappet and its hearing. Theresult is that after the cam has lifted the tappet to unseat the valve,and during the remainder of the greater portion of a cycle of itsrotation, a gap is left between the cam and tappet head until the highpart of the cam again reaches the head and strikes it a violent blow.The blows are usually struck approximately half way between the centerand eriphery of the head and often closer to th% center.

The'frequency of the blows and violence of the impact causes the skin orcase-hardened surface portion to sink into the softer metal there-below,thus leaving indentations on the bearing face of the tappet head, and

inasmuch as the tappet is free to turn in its bearing and does turntherein the bearing face of its head becomes indented, the indentationextending aroundthe face of the head in the form of a ring or annulus.This 7 deformation of the face of the tappet head is apt to seriouslyinterfere with the proper timing of the motor, thereby decreaslng itsefficiency.

The rimary object of this invention is to pro uce a tappet wherein theobjectionable features above referred to are wholly Another reason maybe Specification of Letters Eatent.

Patented Feb. 6, 1191?.

Serial No. 120,740.

eliminated; furthermore, one of the objects is to provide acomparatively inexpensive tappet having such qualifications;furthermore, an object is to provide a one-piece tappet whose body orstem portion is strong, substantial and tough,-and whose head ishardened throughout or substantially throughout. With these and otherobjects and advantages in view, this invention con sists in a one-piecetappet whose head is hardened throughout while its body portion or stemis not hard throughout. The invention further consists of the severalnovel features hereinafter fully described and claimed.

The invention is clearly illustrated in the drawing accompanying thisspecification, in which Figure 1 is a side elevation of a tappetembodying a simple form of'the present invention, a fragment of a'camshaft and a cam being shown in connection therewith;

Fig. 2 is a central, vertical section taken on line 22 of Fig. 1, and

Fig. 3 is a horizontal section taken on line 33 of Fig. 2.

Referring to said drawing, the reference numeral 4: designates a tappetembodying a simple form of my invention; 5, the cam shaft of an internalcombustion engine, and

6, the cam on said shaft which acts on the head 7 of the tappet i. Itwill be understood that in use the tappet is mounted in a bearing (notshown) formed in the engine, and that it lifts and unseats a puppetvalve (not shown), which valve is seated by a spring and the tappettherewith depressed against or toward the cam. its previously mentioned,in high speed motors the cam 6 frequently rotates so rapidly that thetappet does not continuously contact with the cam, but a gap is leftthere-between after the tappet has been fully raised and until the highpart of the cam again reaches it during the course of its rotation. Fig.2 illustrates the parts in a position at the instant where the tappetand high part of the cam have come in contact, it being understood thatprior to this instant the tappet was moving downward but out of contactwith the cam, that the cam rotates in the direction of the'arrowthereon, and that a gap has occurred between the headof the tappet andcam face which existed until the cam came in contact with it. The gap isshown between the face of the head and cam face shown in dotted lines inFig. 2; the width of said gap is somewhat exaggerated for the purposesof illustration. The ordinary tappets, made of case hardened steel andacted upon in this manner, become ineffective in their operation becausethe cam indents the bearing face of the tappet head at the places whereit strikes against it, since the skin or surface portion only is hardand the underlying portions soft.

In the embodiment of my invention the tappet is constructed of lightsteel or a nickel alloy, or any alloy which may be case-hardened. Asusual, the stem portion 8 is round and bored out and tapped for thereception of the adjustment stem (not shown). On one end is formed thedisk-like head 7, which is in the nature of a thin, disk-like flangeextending out from the stem. After the stem has been bored out part WayI extend the bore down to within a short distance of the face 9 of thehead by using a flat-ended or bottom drill so as to leave a fiat orsubstantially flat face 10 at the bottom of the bore. The thickness ofthe wall 11, between the faces 9, 10, should be such that when thetappet is subjected to the case hardening or carbonizing process thehead will become hardened throughout.

Transverse openings 12 are formed in the wall of the stem 8, close tothe head, which afiord communication between the exterior of the stemand the interior of the bore adjacent the head, the purpose of whichwill presently appear. Said openings may be formed by drilling in fromthe sides of the stem. i

- ternal surface portion of the lower end of the bored-out portion andfaces of the openings'12 are sub ected to such hardening process aswell. The result is that the head portion is hardened throughout, orsubstantially sof'depehding upon how thoroughly the hardening process iscarried on, while the stem portion is hardened on its surface portiononly, the body of the stem remaining soft, tough and strong.

Inasmuch as the tappet head is hardened throughout, the danger ofindenting the face of the head is eliminated, making the tappetparticularly eflicient in a high speed motor.

More or less variation and alteration of the exact form of the inventionshown and described is possible without departing from the spirit ofthis invention. I desire, therefore, not to limit myself to the exactform set forth, but intend in the following claims to point out all ofthe invention disclosed herein.

I claim as new and desire to secure by Letters Patent 1. A tappet,comprising acase hardened single piece, consisting of a hollow stemportion formed with a head on one end, there being openings through thestem portion adjacent the head whereby the head and adj acent stemportion may be case hardened on their outer and inner sides.

2. A tappet comprising a case-hardened single piece, consisting of astem portion and a disk-like head portion, there being openings throughthe stem portion adjacent the head for the admission of a carbonizingelement.

3. A tappet comprising a single piece, consisting of a stem and adisk-like head on one end, there being a hollow space in the stemadjacent the disk, opening out through the Wall of the stem, and thesurface portion of the head and surface portion of the hollow of thestem adjacent the head being case hardened.

4. A tappet comprising a single piece, consisting of a stem havin adisk-like head on one end, said stem having a bore extendingtherethrough terminating adjacent the head. to thereby leave a thin wallbetween the faceof the head and bore, and there being openings adjacentthe head leading out from said bore, the external surface portion ofsaid stem and head and the internal surface portion of part of the stem,head and openings being hardened.

GEORGE R; RICH.

